The effect of aged garlic extract compared to placebo on aerobic fitness and arterial stiffness in sedentary adults

INTERVENTION: This randomised double‐blind placebo‐controlled trial of 12 weeks will examine the effect of aged garlic extract on aerobic capacity during moderate intensity exercise, measured by predicted VO2max, and arterial stiffness, indicated by pulse wave velocity and augmentation pressure, in a group of sedentary adults, compared with placebo. The active treatment group will be allocated to two daily capsules of aged garlic extract (1.2 g Kyolic Reserve, 1.2 mg S‐allylcysteine (SAC)). Compliance will be assessed by return of trial capsules, as well as diary entries. Patients will be instructed to mark each day in provided calendars when they have taken the trial and prescription medications, and bring the calendar and the remaining trial medication to their next appointment. CONDITION: elevated pulse wave velocity sedentary PRIMARY OUTCOME: Aerobic capacity will be measured by VO2max (mL/kg/min) using the YMCA Submaximal Cycle Ergometer Test. The test is a non‐invasive, submaximal exercise protocol in which heart rate‐workload points are obtained and extrapolated to age‐predicted maximal heart rate of the participant – calculated by subtracting the participant’s age from 220. VO2max is then predicted from the determined maximal workload (the maximal amount of work produced). ; The test consists of 3x3‐minute stages. The ergometer’s resistance is increased incrementally – each stage selected with respect to the participant’s heart rate in the third minute of each stage. ; The first stage will be set at 25 Watts, Stages 2 and 3 are set according to the participant's heart rate in the 3rd or 4th minute of the preceding stage, following the YMCA submaximal cycle test protocol by Nieman D (2010 in Book: Exercise Testing and Prescription. McGraw‐Hill Education) Pulse wave velocity (PWV) and augmentation pressure will be measured before and after each exercise testing session using a Mobil‐O‐Graph – an electronic blood pressure monitoring system, comprised of an arm cuff and software tool for Pulse Wave Analysis. The device has been shown to be reliable in estimating PWV (Salvade et al., 2015). This is a composite primary outcome. SECONDARY OUTCOME: Lactate (hLa) to RPE ratio ; Blood samples will be obtained from the right index finger, using an Accu‐Chek Safe‐T‐Pro Plus single use lancing device (www.accu‐chek.com.au) and analysed using the Lactate Pro 2 analyser (www.lactatepro.com.au) (Coutts 2007; Miller 2012). hLa:RPE will then be calculated by dividing the blood lactate concentration by the corresponding RPE score, and multiplying it by 100 (Garcin 2002). This ratio will be determined for each of the 3x3 min stages of the exercise test, to ascertain whether supplementation with aged garlic extract has an effect on perceived exertion at a relative intensity, compared with placebo. Level of exertion by Borg’s Rated Perceived Exertion (RPE) 10‐point scale (Borg, 1998) INCLUSION CRITERIA: 1) International physical activity questionnaire (IPAQ) score of 2 or below (minimally active) 2) Elevated pulse wave velocity and / or augmentation pressure (higher half of reference values, adjusted for age and gender) (Nunan 2012; Nunan 2014)